err_http_headers_sent]: 从服务器获取邮件时发送到客户端后无法设置邮件头

Question

我正在尝试使用 attachment.I 获取电子邮件 that.i 使用了 imap 和 MailListener2 库 我面临以下错误，如 image.i 所示 我正在使用 attachment.can 谁能告诉我错过了什么？

这是我用来获取电子邮件的代码。请提供任何解决此错误的方法。

async function mailreply(req, res) {
    Employee.email_reply(req.params.email, function (err, employee) {
         
         var imapConfig = {
            user: '*****',
            password: '****',
            host: 'imap-mail.outlook.com',
            port: 993,
            tls: true,
            tlsOptions: {
                rejectUnauthorized: false
            }
        };

        var imap = new Imap(imapConfig);
        imap.once("ready", checkMail);
        imap.once("error", function (err) {
            console.log("Connection error: " + err.stack);
        });
        imap.connect();
        function checkMail() {
            imap.openBox("INBOX", false, function (err, mailBox) {
                if (err) {
                    console.error(err);
                    return;
                }
                imap.search(["UNSEEN", ["FROM", req.params.email]], function (err, results) {
                    if (!results || !results.length) {  
                        req.flash('error', 'No reply from selected user.')  
                        res.locals.message = req.flash();   
                        res.redirect(nodeSiteUrl+'/dashboard');  
                        imap.end(); return; }
                });
            });
        }
        
        
        
        
        var mailListener = new MailListener({
              username: "******",
              password: "******",
              host: "imap-mail.outlook.com",
              port: 993, // imap port
              tls: true,
              connTimeout: 10000, // Default by node-imap
              authTimeout: 5000, // Default by node-imap,
              tlsOptions: { rejectUnauthorized: false },
              mailbox: "INBOX", // mailbox to monitor
              searchFilter: [ 'UNSEEN', ['FROM', req.params.email] ], // the search filter being used after an IDLE notification has been retrieved , 
              markSeen: false, // all fetched email willbe marked as seen and not fetched next time
              fetchUnreadOnStart: true, // use it only if you want to get all unread email on lib start. Default is `false`,
              mailParserOptions: {streamAttachments: true}, // options to be passed to mailParser lib.
              attachments: true, // download attachments as they are encountered to the project directory
              attachmentOptions: { directory: "attachments/" } // specify a download directory for attachments
        });
            
        mailListener.start();
        
        mailListener.on("server:connected", function(){
          console.log("imapConnected");
        });
        
        mailListener.on("error", function(err){
          console.log('hello');
        });

        mailListener.on("mail", function(mail, seqno, attributes){
            console.log(seqno)
            let attachments = [];
            var attachment = mail.attachments;
            if(attachment) {
                for(var i = 0, len = attachment.length; i < len; ++i){
                    attachments.push(attachment[i].fileName);
                }
            }
            passDatatoPage(mail, attachments);
            mailListener.stop();
        }) 
       
        mailListener.on("attachment", function(attachment){
            let filepath = './public/attachment/receive/';
            let output = fs.createWriteStream(filepath + attachment.fileName);
            attachment.stream.pipe(output).on("end", function () {
                console.log("All the data in the file has been read");
            }).on("close", function (err) {
                console.log("Stream has been cloesd.");
            });  
        });
    
    
        function passDatatoPage(mail, attachments) {
            var sender = mail.to[0].address;
            var senderName = mail.from[0].name;
            var reciver = mail.from[0].address;
            const date = moment(mail.date).format('LL');
            var subject = mail.subject;
            var message = mail.text;
            //console.log(attachments);
            var result = attachments.map(function(val) {
                return val;
            }).join(',');
            var attachmentArr = result.split(',');
            console.log(attachmentArr)
            res.render('email-reply', { title: 'Email Reply', to: sender, senderName: senderName, from: reciver, date: date, subject: subject, msg: message, attachments: attachmentArr});
        }
        
    });
};
exports.mailreply = mailreply;

Answer 1

我相信 imap.once("ready", checkMail); 触发后请求可能已经完成，这是竞争条件。完成后，连接将关闭，因此您无法再更改已发送的请求。在完成请求处理程序之前，您需要添加一些代码来等待所有事件完成。

Answer 2

你需要做两件事

1. 尝试用 try catch 块结束代码
2. 不要从发件人那里获取所有电子邮件，只获取需要的邮件 例如，使用邮件 ID 获取邮件，如下所示 获取该消息 ID 并根据以下代码更改搜索过滤器 （使用下面的搜索过滤器按 ID 查找消息）

var mailListener = new MailListener({
              username: "******",
              password: "*****",
              host: "imap-mail.outlook.com",
              port: 993, // imap port
              tls: true,
              connTimeout: 10000, // Default by node-imap
              authTimeout: 5000, // Default by node-imap,
              tlsOptions: { rejectUnauthorized: false },
              mailbox: "INBOX", // mailbox to monitor
              searchFilter: [ ['HEADER','IN-REPLY-TO',messageId] ], // the search filter being used after an IDLE notification has been retrieved , 
              markSeen: false, // all fetched email willbe marked as seen and not fetched next time
              fetchUnreadOnStart: true, // use it only if you want to get all unread email on lib start. Default is `false`,
              mailParserOptions: {streamAttachments: true}, // options to be passed to mailParser lib.
              attachments: true, // download attachments as they are encountered to the project directory
              attachmentOptions: { directory: "attachments/" } // specify a download directory for attachments
        });